In wireless communication systems, the desired or wanted signals coexist with a wide band of unwanted signals, where the power of the unwanted signals can often be much higher than the power of the wanted signals.
A filter is typically employed within wireless receivers to reject the unwanted signals. In addition, to optimize the system, an adjustable or adaptable gain circuit (AGC) associated with the filter is necessary to raise the power level of the wanted signal as early as possible within the receiver stages. However, a gain circuit integrated with the filter may have a slow response time when the gain is changed. The filter's bandwidth and the AGC settling time are typically the primary response time limitations for such circuits.
There is, therefore, a need in the art for an adjustable gain filter mechanism with fast gain response.